C.C. Carbon et al/Perception 2014
Let’s try an experiment: Draw a face. Nothing fancy, just an oval with eyes, nose, mouth, some hair.
What you’ve produced probably looks like a cartoon Neandertal. Just about everyone tends to draw faces with the eyes too high on the head, resulting in a low forehead and a rather cretinous look.
It’s not just a matter of artistic talent. Psychology researchers (not to mention generations of art teachers) have noticed that everyone does it. That got Claus-Christian Carbon, who studies visual perception, wondering. Why don’t we know where people’s eyes are on their head? After all, humans are intensely social creatures who are highly attuned to reading each other’s faces. The eyes, in particular, get a lot of our attention.
In reality, your eyes are right about in the middle of your head, measured vertically. But most people draw them definitively above center.
“Even in painting courses, people start with exactly this bias,” Carbon says. “It’s absolutely familiar to researchers, but there was nothing in the [scientific] literature about it.” (You might remember Carbon from my recent post about the 3-D Mona Lisa; I learned of his work studying visual perspective in that painting when I called him about this study.)
Sadly, they only did a little better by copying.
Finally, Carbon and Wirth looked at depictions of faces in research papers by three well-known researchers who study face recognition. And yep, the pros failed.
So the researchers came up with three hypotheses, reported in March in Perception, to explain why normal people, and even people who study faces for a living, might not be able to put eyes in the right place. Here they are, in my own subjective order of increasing weirdness:
- Hair-as-hat hypothesis: People don’t think of the hair as part of the head, but as sitting on top of the head like a hat (at least when they’re drawing a face). So they relate eye position to what’s seen as the “face” rather than considering where the eyes are on the head as a whole.
- Head-as-box hypothesis: People don’t take the convexity (roundness) of the forehead into account, so the top of the head is assumed to be lower than it really is.
- Face-from-below hypothesis: Babies first see faces mostly from below, and this view sets a mental map of sorts that is hard to erase later in life.
So far, the results seem to favor the second hypothesis, head as box. Analysis of the relative length of the faces that people drew showed the heads to be too short compared with the models they were based on. The hairlines, on the other hand, were drawn in the correct relative position, causing the forehead to be too small.
“As humans we have trouble assessing round shapes,” Carbon says. “Herman Munster has a really nonconvex head. That’s maybe the only person in the world whose head you might estimate correctly.”
To nail down whether the head-as-box effect is a general phenomenon, the researchers plan to see whether people have similar misperceptions of other rounded objects. “We will start with animal faces and then go further to everyday objects such as teakettles, cups, mugs and bottles,” Carbon says.
While misplaced eyes and many other visual illusions make it seem like our brain is making mistakes, “these perceptual failures are often actually extreme performance,” Carbon says. The area from the eyes to the mouth contains the most important information about a person’s emotional state, so that’s what we tend to zoom in on.
As for why we keep drawing people looking like Neandertals, Carbon says it’s just a coincidence. But as long as we keep doing it, the team writes, “Neandertals live on, at least in our depictions.”
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